Manufacture of hydrofluoric acid.



H. B. BISHOP. MANUFACTURE 0F HYDRLFLUORIC ACID.

.APPLICATION FILED AUG. U. 19H.

Patented Aug. 17, 1915.

2 SHEETS-SHEET I.

Qaay

employed, asulfate f HOWARD BERKEYRIsHoP, or NRW YoRK, N. Y., AssIeNoR 'ro GENERAL cnEMrcAL COMPANY, or NEW YORK, N. Y., A coRroIArIoN or NRWA Y'oRK.

To-alliwhomft'may concern: ,l L

Beit known that I, HOWARD BERKEY BrsHor, a citizen of the United States, and

'county of Kings, city and a resident of the borough caff Brooklyn,

York, have invented certain new and useful Improvements in the Manufacture of Hydrofluoric Acid, of which the following is a speciiic'ation.I

Myl invention relates to the art manu-` to producev a substantially pure hydrofluori'c acid in a practically continuous manner, while at the same time producing a granular and easilyhandled residue whichl chemically `consists mainly ofa'salt of the acid employed which is, when sulfuric acidhas vbeen Another object is the production of-a process by which the evolutionv of hydroiuoric.v

acid, in the form of a gas, is substantially constant in volume.

Other objects of my invention will appear in the following description 'of my process and the preferred embodiment of anapparatus for the accomplishment thereof.

Heretofore hydroiuoric acid was made by intermittent processes which comprised, in general, heating charges of sulfuric acid and fluor spar in vessels preferably of iron or lead, provided with removable hoods or heads -through which the evolved gas was conducted to suitable condensing devices.

The materials' weremixed togetherin the vessel and then heated to a suitable tem` perature for causing chemical reaction and consequent gas evolution, this temperature f being maintained until the reaction ceased.

' new charge might then After each charge had beenheated the head was removed and the hard solidified and f tenacious cake of calcium sulfate, forming a lining on the bottom of the vessel," was broken up of `luorid and sulfuric acid the charge was of the propertiesof the materials used it was diiicult if not impossible to obtain a homo- Specification of Letters Patent.

State of New ing drawingfin which and removed vfrom the vessel. A

be introduced. The mixing ofl accomplished by hand before ltheapplicationof heat and on account4 MANUFATURE 01?' HYDBOFLUORIG 'A0111 Patenten Aug. 17, 1915.

Application filed August 8, 1911. Serial No. 643,034. i

being given'of in gusts and thus putting a heavy duty upon the condensing device while' during a great proportion of the time of evolution, the gas flow vwas so small as to utilize but a smallfraction of the capacity of the condensing apparatus. v

My invention comprisesU a process of manu facturing hydrofluoric acidjby which the disadvantages of formerprocesses and apparatus are avoided. lOneforl'n of apparatus which I may employ for carrying out my prdcess is' illustrated the accompany- Figure l shows said apparatus in longitudinal, vertical section and Fig. 2 shows the sam` e infront elevation. The decomposition vessefcom risesa cylinder 1 which may consist of a anged, cast iron water pipe of abo'ut twelve' feet in length and forty inches in diameter, said around the cylinder being separatedtherefrom by the annular space 4. This space is cylinder being rotatably mounted on rollersA 2 adyustably ymounted on a brick-Work foundation 3. The brick-work is extended lso of therylinder withla Dutch oven 5 the rear end of which is shown in Fig. 2. Flame and combustion gasesare thusconducted 'from the furnace 5 through the flues 5 to the space f for the purpose of heating the cylin- Qder l, the products of combustion passing around said cylinder and through the outl i let flues 6 nearv the' forward end of the cylinder and esca ingl through the chimney 6- Albanie 6 o brick-work extends longitudinally of the 'cylinder between the inlet iues 5 and the outlet lues 6 and projects across space 4, into close proximity to the cylinlder soas to cause the gases entering the fluesv5 to pass around'the cylinder before enteringthe outlet iues 6. Since the heat from the furnace is. first brought into contact with the cylinder near the discharge end thereof,'that en d is maintained at a higher degrec-of temperature thanl the feed end of the cylinder. To the feed end of the cylinder is 4bolted an annular ring 7 lthe periphery of which forms a track for cooperation with.

the rollers 2 at the forward or feed end-of thecylinder, which is'lclosed by a plate 8. This plate is and the central aperture of ico secured to the I-beam 9 extending transof the apparatus versely across the front and secured to the brick-work thereof suitable brackets 10. The` plate '8 is thus held rigidly and non-rotata ly in position -to close the opening in the annular ring 7.V

Al-p'acking ring 11 is secured to -the ring 7 an said packing ring andv its associated.

packing serves to maintain a gas tight connection between the rotatable and non-rota- 'table parts. The plate 8 is formed with a gas outlet conduit 12 and with a feed conduit 1 3", the conduits preferably being cast vintegrally' with the-plate and the feed conduit extending angularly upward externally i of the cylinder. The upper end of the feed conduit is preferably formed by apipe 14 :suitably joined to the portion 13 of. said conduit. The upper end of the pipe 14 is .closed by'a plate 15, upon the removal of which the conduit, las-willbe a parent, may easily be cleaned., and near sai upper end the pipe 14 is provided with avertical .branch` 16, the upper end of'which leads to theagitating or imixing device 17 the latter being of any suitable construction. A valve 18 is proi' 'vided in Said branch pipe to: control the feed of materials fromthe mixing device to the l' feed' conduit.

To the rear end of the cylinder l is bolted an ,extension 19,;l to the end of 'which is sev cured -a-"discha'ge device 20. 'Surrounding' `the cylinder and abutting the flange thereof is Aa circumferentially arranged series of- 'I wedges 21 having beveled outer surfaces. There maybe any desired number of said wedggzgcsand they may be spaced at suitable distances from each other. Coacting' with each wedge 21 is a complementary, oppo` I sitely disposed wedge 21.l The beveled surfaces of said wedges 21 and 21 engage with.- a @insg-22, the outer circumference .of which for atrack for coperation with the rollers'2 at the'discharge end of the cylinderl i and the inner 'surface' of which is doubly beveled to coperate with-the beveled `sur- 1'. "pa'ss through the -wedges 21 and 21', and toothed gear these bolts will not only secure the partsjreactuated in anysuitable way as for instance by a train of ley 24.

I n the operation of iny device," a chargeof i for example, iuorspar and sulfuric acid is introduced inI which these "materials are thoroughly agi- "if tatcd and mixed and from which, by the OP- .-'e'ration'ofthe valve I8, the more or less liq- 'llid mixture'is introduced into thefeed con- `motion by the rotation of 24 and heated from the furnace 5'.' The ref action between the luorid and the sulfuric: acid to form hydrofiuoric acid does not take".

.facesfof thewedges 21 and 2 1. The boltsl for securing the extension 19 to the cylinder nuts `on the ends' of gears operated by 'a power pnl-- in properproportions into the agitating apparatus 17 duit and by this means inte the decomposing previously setiin' cylinder 1, which has been the power pulley place in the mixer 17 to any great extent on account of the .relatively cylinder, however, hydroiiuoric acid gas is l n low temperaturev thereoI. Upon reaching the interior of theimmediately evolved'. The drum continuously presents new,-heated surfaces to the charge because of its rotation, and the charge itself is continuously turned over and thoroughly agitated. The charge, either bee cause of the introduction of subsequent charges or because of a slight inclination of the drum' the discharge end thereof, being agitated all the time. Moreover, Vas the charge moves tlward the rear end of the cylinder it gradua y of the drum, resulting in carrying 011 the gas evolving reaction to a degree beyond that which would take place at lower temperatures. Each new charge when introduced into the decomposing cylinder, upon the materials therein and is not s ubjected immediately, therefore, to the temperature of the walls of the cylinder and the evolution of` gas is not' so sudden and abundant as would otherwise bethe c-ase. When ,gradually makesits way toward' comes into contact with hotter portions' falls directly the charge' reaches the discharge hopper 20 the -reactionis complete and the calciumI Asulfate product may bejremoved. ,The remaval of the sulfate may take place .at suit-` able. intervals andl in regulatable amounts and vhas no material eHect `on the gas iow.

The gas evolved, as will be readily under- -Y ma.

stood, escapes through the outlet 12 and is then conducted .to suitable condensing appa-A It will be 'seen that `by setting the valve' 18 in partially open position, andin t 1f .troducing the iiuorid and' sulfuric acid coni tinuously, a wholly continuous process ratus.

provided. Because the reaction takes place :ggf-

lat gradually increasing temperatures, the 1 gas evolution is. substantially constant as `comparedwith that inthe processes hereto- 'forev used; a -continuous lflow, therefore,

assesthrough the outlet passage. Itis-to llie noted that even if the mixing is donezinA` termittently in the mixing device 17 and 'after each--m1xing process .the mixture formed is runyinto the decomposing device .-1, thel iow of gas at the outlet pipe 12 is neverthe-.

lessf'continuous and substantially constant'.

in volume. Because the charges are constantly and thoroughly agitated, the sulfate collected from the discharge end of the devicel consists of small, loose, `granular 'particles andv consequently is easily handled.

Many advantages due to the use of my device will be apparent froma mere comY parison between it and former devices for the same purpose, but some ofthe special advantages maybebriefly mentioned, l. The gaslow is Substantially uniform and constant and the vgas condensing apparatusis in effective operation substantially all of the time,-which is not the case in the old processes. 2. TheA calcium sulfate is removed in about the proportion and rate at' which it is formed, and in a loose, granular and easily handled form, and it `does notV have to be broken out from the apparatus by cr'ow bars or'the like as is the case in the old-processes. 3. -The apparatus is substan- 'tially gasytight; there ,are few if any leaks and the health and comfort of the -attending laborers. is very' little disturbed, as' against the considerable disturbances in these direc- -tions occasioned by the old processes. 4.

One gas condensing system can be made to take carev of the product of more than four times the quantity. of fluorspar decomposed in apparatus of the old type, and 4the four as condensing systems therein usually employed. '5. lThe fuel consumption is reduced by about one-half ofthe fuel consumed in the old processesfor the same-quantity of 'luorspar. '6.' lThe repairs are less thanonefourth the repairs inthe old apparatus for the same .weight of iiuorspar worked up.

7. The space required is-less than one-fourth of that which would be required under the old -processes for the same weight of fluorspar worked up. 8. The yield of inal product is about one-eighth better than by the o ld processes.A 9. Less of the silica which is usually contained in fluor-'spar is'carried over into the finished product 1n my process than in the old processes. -10. The time required for commercially complete decompo sition of charges of the same size is much shlorter by my new `process than by` the old processes.

The proportions of iiuorspar and sulfurie acid and the tem erature of operation may be widely varied Eutin practieI prefer to use 200 pounds of 99% sulfuric acid at a temperature of about 80 F.'or less, to

' which I add, stirring the while,150 pounds of finely ground liuorspar. 'The temperature Within the cylinder near the discharge end thereof is preferably maintained at about 600 F. and near-the charging or feed end atabout 240 to 260 F. After having Y ce mixed the Ycharge in the device'l?r for a' minute or ltwo and before any appreciable reaction has taken place, it is run into the decomposition cylinden vSuccessive charges are added in the same way and the corresponding amounts of calcium'asulfate are withdrawn from the 'device20. Three or four hours are required for a charge such 'as has been described to pass through my preferred form of apparatus. `I ind it de.- sirable and suitable to introduce l such charges and remove the corresponding yforty minutes also charge the mixture of luorspar and 'and continuously Abreaking mass ofthe reacting materials during the acid, which comprises heating acid, which comprises amounts of sulfate under these conditions of' apparatus and temperatures about every although, of course, I may acid continuously into the decomposing device since it is so constructed that the revolving of the cylinder need not be inter. rupted duringsuch charging.

I claim: l

1. The process of making hydrofluoric acid, which comprises heating a fluorid. and an acid, capable of reacting to produce a solid in the form of a hard` cake, and con'- tinuously breaking up the entire masslof the reacting materials during the reaction thereof, whereby the formation of said hard cake is prevented. 2. The process of maln'ng hydroluoric acid, which comprises applying heat to a fluorid and an acid, capable of reacting to produce a solid in the form of a hard cake,

acid, which comprises simultaneously heating to gradually increasing temperatures a fluorid and an acid, capable of reacting to produce a solid in the form of a hard cake,

reaction thereof, whereby the formation of `said hard cake is prevented.

4. The process of making hydrofluoric acid, which comprises heating calcium iuorid and an acid, capable of reacting to produce a solid in'the form of a hardcake, and continuously breaking up the entire mass of reacting materials during the reactionthereof, whereby the formation of said hard cake is' preventedf 5. The process of making hydrofluoric calcium luorid and sulfuric acid and'continuously breaking up the en'tire mass of reacting materials during thereaction thereof, whereby the formation of a hard cake of calcium sulfate is .prevented.

6. -The process of making hydrofluoric mixing calciumV fluorid and sulfuric acid and subsequently simultaneouslyv heating and continuously breaking upthe entire mass of reacting maup the `entire the formation ofV a hard cake lof calcium sulfate is prevented.

- '7; The processfof making hydrofluoric acid, which comprises. mixing calcium, iuorid and sulfuric acid and subsequently simultaneously heating to gradually increasing temperatures and continuously breaking up the entire mass of reacting materials during the reaction thereof, whereby the formation of a hard cake of calciumv sulfate is prevente 8. The process of 'making hydroiuoric l' acid Whichconsists in mixing charges of tinuously,

calcium fluorid and sulfuric acid and consimultaneously. agitating and I heating to gradually increasing temperacontinuously,

i tures previously mixed charges.

heating to gradually., increaslng temperatures the previously agitated substances. A.

1 0.` Theprocess of making. hydrofiuoric peratures,

acid which 'consists iuorid and sulfuric multaneouesly agitating said materials and heating them to gradually increasing temcontinuously condensing the evolved hydroiuric acid and removing the loose, granular calcium sulfatei In testimony whereof, I have hereunto set my hand in the presence of two subscribing witnesses.

HOWARD BERKEY s IsHOP. Witnesses: z

` JOHN A. FnReUsON,

JOHN A. KEHLENBECK. Y.

in .l agitating calcium acid, continuously, si-4 

